It’s no secret that insects are drawn to light. But it turns out that the light source makes all the difference in the size of the gathering.
Standard incandescent bulbs have been used for decades by research scientists to lure insects into traps. Such collections have been critical to monitoring and studying vector–borne diseases such as malaria, West Nile virus and Leishmaniasis.
And while traditional bulbs allow scientists to gather the tiny specimens in the field for further study in the lab, solid–state lighting in the form of LEDs appears to offer a range of advantages, including a higher insect count.
In recently published research, Leonard E. Munstermann, a senior research scientist at the Yale School of Public Health, described how his team removed incandescent bulbs from standard insect traps and outfitted them with LED bulbs. In field tests in French Guiana and Colombia, the LED–based traps captured up to 50 percent more of the sand flies responsible for the transmission of Leishmaniasis.
The higher insect yield is explained by the precision of the LED’s wavelength. Its emission can be accurately set to within a few nanometers. That means that an insect that is attracted to 400–nm light (a deep violet color that is on the far edge of the visible spectrum) can be enticed with bulbs that emit almost exclusively at 400 nm. The bulbs can easily be swapped if a longer or shorter wavelength is desired. A standard incandescent white bulb, meanwhile, emits light over a very broad spectrum. The majority of its energy is emitted as infrared radiation, an area of the spectrum that is invisible to most insects and ends up simply being wasted as heat.
“It opens up a whole new area of research in entomology. We have a lot of work to determine optimal wavelengths,” said Munstermann, who developed the LED–based trap with doctoral student Lee W. Cohnstaedt and his brother, an electrical engineer at Harvard University.
In addition to tunability, LEDs also use considerably less power than incandescent bulbs. This is especially important for researchers operating on a limited budget and in remote areas where fresh supplies of batteries are unavailable. Munstermann said that the LED–based light traps also are smaller and lighter, a factor that becomes increasingly significant when the traps have to be hauled long distances to a study site.
“I’m going to use them for all of my work for now on. I’ll never go back,” Munstermann said.
Details of the research appeared in the June issue of the Journal of the American Mosquito Control Association.